1. Field of the Invention
The present invention generally relates to cushion assemblies for use on a patient interface device in a pressure support system that supplies a flow of gas to the airway of a patient, and, more particularly, to cushion assemblies which include one or more adjustable stabilization members. The invention further relates to patient interface devices that include such cushion assemblies.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation (NIV). It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), chronic obstructive pulmonary disease (COPD), or congestive heart failure (CHF).
Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask (i.e., a full face mask), on the face of a patient to interface the ventilator or pressure support system with the airway of the patient so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
Typically, patient interface devices include a mask shell having a cushion attached to the shell that contacts, and seals against, the surface of the patient. The mask shell and cushion are held in place by a headgear that wraps around the head of the patient. The mask and headgear form the patient interface assembly. A typical headgear includes flexible, adjustable straps that extend from the mask to attach the mask to the patient.
Because such masks are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP to treat OSA, the patient normally wears the patient interface device all night long while he or she sleeps. One concern in such a situation is that the patient interface device is as comfortable as possible, otherwise the patient may avoid wearing the interface device, defeating the purpose of the prescribed pressure support therapy. It is also important that the interface device provide a tight enough seal against a patient's face without discomfort.
Full face CPAP masks that include one chamber that covers the nose and mouth have a single opening in the sealing flap to accommodate both the nose and mouth. In encompassing both the nose and mouth, the sealing perimeter of a full face mask must cover a large area wherein the anatomical contours typically vary significantly. Such varying contours can make the seal more susceptible to stability and leak issues. Accordingly, considerable forces are often necessary in order to achieve a satisfactory seal. Such forces generally make such masks uncomfortable to wear, particularly for extended periods of time.